U.S. patent number 9,067,293 [Application Number 13/250,509] was granted by the patent office on 2015-06-30 for accessory clamp for a power tool.
This patent grant is currently assigned to Robert Bosch GmbH. The grantee listed for this patent is Walter Bernardi, Brian Knoles. Invention is credited to Walter Bernardi, Brian Knoles.
United States Patent |
9,067,293 |
Bernardi , et al. |
June 30, 2015 |
Accessory clamp for a power tool
Abstract
A clamping device for clamping an accessory to a power tool
includes a first flange, a spindle member, and a cam member. The
first flange is coupled to a drive system of the power tool and is
configured to receive the accessory. The spindle member defines a
longitudinal axis and includes a second flange provided on an end
of the spindle member and a follower member provided on an opposite
end of the spindle member. The cam member includes a cam surface
configured to interact with the follower surface, the cam member is
rotatable about the longitudinal axis to a clamped position and to
an unclamped position. In the unclamped position the accessory is
removable from the first flange, and in the clamped position the
accessory is clamped between the first flange and the second
flange.
Inventors: |
Bernardi; Walter (Highland
Park, IL), Knoles; Brian (Springfield, IL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Bernardi; Walter
Knoles; Brian |
Highland Park
Springfield |
IL
IL |
US
US |
|
|
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
|
Family
ID: |
47089145 |
Appl.
No.: |
13/250,509 |
Filed: |
September 30, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130082449 A1 |
Apr 4, 2013 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24B
45/006 (20130101); B24B 23/04 (20130101); B24B
23/022 (20130101); Y10T 279/33 (20150115); Y10T
279/3451 (20150115) |
Current International
Class: |
B23B
31/02 (20060101); B24B 23/02 (20060101); B24B
23/04 (20060101); B24B 45/00 (20060101) |
Field of
Search: |
;279/141,150
;83/698.11,782,597,697 ;30/330,339,331 ;451/356,357,359 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3405885 |
|
Jan 1986 |
|
DE |
|
0253181 |
|
Jan 1988 |
|
EP |
|
0495181 |
|
Jul 1992 |
|
EP |
|
2005063439 |
|
Jul 2005 |
|
WO |
|
Other References
International Search Report and Written Opinion in corresponding
PCT application (i.e., PCT/US2012/057786), mailed Jul. 10, 2013 (10
pages). cited by applicant.
|
Primary Examiner: Gates; Eric A
Assistant Examiner: Su; Chwen-Wei
Attorney, Agent or Firm: Maginot Moore & Beck LLP
Claims
What is claimed is:
1. A clamping device for clamping an accessory to a power tool
comprising: a first flange coupled to a drive system of the power
tool and configured to receive the accessory; a spindle member
defining a longitudinal axis and including a second flange provided
on an end of said spindle member and a follower member provided on
an opposite end of said spindle member, said second flange defining
a circular periphery and a center point that is misaligned with
said longitudinal axis; and a cam member including a cam surface
configured to interact with said follower member, said cam member
being rotatable about said longitudinal axis to a clamped position
and to an unclamped position, in said unclamped position the
accessory is removable from said first flange, and in said clamped
position the accessory is clamped between said first flange and
said second flange.
2. The clamping device of claim 1, further comprising: a biasing
member positioned between said follower member and said second
flange, said biasing member configured to urge said second flange
toward said first flange.
3. The clamping device of claim 1, wherein: said cam member defines
a circular periphery aligned with said longitudinal axis, and said
cam surface extends from said circular periphery of said cam member
and extends substantially completely around said longitudinal
axis.
4. The clamping device of claim 3, wherein: said cam surface
includes a first inclined surface and a second inclined surface,
and said follower member includes a first protrusion configured to
interact with said first inclined surface and a second protrusion
configured to interact with said second inclined surface.
5. The clamping device of claim 1, wherein: said first flange
includes a plurality of protrusions configured to be received by a
plurality of protrusion openings formed in the accessory, and said
spindle member includes a chamfered portion configured to bias the
plurality of protrusion openings against the plurality of
protrusions when the cam member is in the clamped position.
6. The clamping device of claim 5 wherein: said accessory defines a
spindle opening through which said spindle member is configured to
extend when said first flange receives said accessory, and a wide
portion of said chamfered portion is wider than said spindle
opening defined by said accessory and contacts said spindle opening
defined by said accessory when said cam member is in said clamped
position.
7. The clamping device of claim 1, wherein said cam member defines
a detent configured to receive at least a portion of said follower
member when said cam member is in said unclamped position.
8. A clamping device for clamping an accessory to a power tool
comprising: a first flange coupled to a drive system of the power
tool and configured to receive the accessory; a spindle member
defining a longitudinal axis and including a second flange provided
on an end of said spindle member and a follower member provided on
an opposite end of said spindle member; and a cam member including
a cam surface configured to interact with said follower member,
said cam member being rotatable about said longitudinal axis to a
clamped position and to an unclamped position, in said unclamped
position the accessory is removable from said first flange, and in
said clamped position the accessory is clamped between said first
flange and said second flange and said cam surface is separated
from said follower member.
9. A clamping device for clamping an accessory to a power tool,
comprising: a first clamp member coupled to a drive system of the
power tool and including a plurality of protrusions configured to
be received by a plurality of protrusion openings formed in the
accessory; an actuator rotatable about an axis of rotation to a
clamped position and to an unclamped position; and a second clamp
member movable in a direction parallel to said axis of rotation and
defining a chamfered surface at least partially positioned against
a spindle opening defined by the accessory, wherein when said
actuator is rotated to said clamped position the accessory is
clamped between said first clamp member and said second clamp
member, and said chamfered surface biases the plurality of
protrusion openings against said plurality of protrusions, and
wherein the accessory is removable from said first clamp member
when said actuator is rotated to said unclamped position.
10. The clamping device of claim 9, further comprising: a spindle
member extending from said second clamp member and defining an axis
of oscillation that is aligned with said axis of rotation, wherein
said second clamp member defines a circular periphery and a center
point, and wherein said center point is offset from said axis of
rotation and said axis of oscillation.
11. The clamping device of claim 9, further comprising a biasing
member positioned between said actuator and said second clamp
member, said biasing member configured to urge said second clamp
member toward said first clamp member when said actuator is in said
clamped position and when said actuator is in said unclamped
position.
12. The clamping device of claim 9, wherein the power tool is a
rotary power tool or an oscillating power tool.
Description
FIELD
This patent relates generally to power tools and particularly to a
clamp for clamping an accessory to a power tool.
BACKGROUND
Oscillating tools are handheld power tools used by professional
craftsmen, handymen, and hobbyists. The typical oscillating tool is
a handheld tool configured for use with a variety of accessory
bits/tools that can be used for cutting, carving, drilling,
sanding, polishing, and many other applications. One specific
example of an oscillating tool is the Dremel.RTM. Multi-Max.TM.
oscillating tool, which is sold by the Robert Bosch Tool
Corporation.
The typical oscillating tool includes a housing that encloses an
electric motor. Rotation of the motor is coupled to a transmission,
which converts the rotation into oscillating movement. An accessory
tool holder extends from a front portion of the housing and is
coupled to the transmission, such that the tool holder oscillates
when the motor is coupled to a supply of electrical energy. In
particular, the tool holder, and any accessory bit connected
thereto, oscillates through a range of movement of about two
degrees (2.degree.) to three degrees (3.degree.) at a frequency of
approximately 350 Hz. Typically, the oscillations cause a working
portion of the accessory bit to move in a controlled side-to-side
motion, which produces minimal dust during cutting operations.
The accessory bit is typically connected to the accessory tool
holder with a removable fastening member and a washer. The
fastening member is removed from the tool holder with a separate
hand tool when a user desires to change or replace the accessory
bit. The fastening member and the washer are reconnected to the
tool holder with the separate hand tool when the replacement
accessory bit is positioned on the accessory tool holder.
The fastening member works well to secure the accessory tool to the
accessory tool holder. Frequently, however, the separate hand tool
is small and easily misplaced. Additionally, users typically desire
to change the accessory bit quickly to reduce the amount of time
spent configuring the oscillating tool.
Therefore, it is desirable to provide an accessory tool holder,
which securely connects to the accessory bit, does not require the
use of a separate hand tool, and that is quickly configured when
the user desires to change or replace the accessory tool.
SUMMARY
According to one embodiment of the disclosure, a clamping device
for clamping an accessory to a power tool includes a first flange,
a spindle member, and a cam member. The first flange is coupled to
a drive system of the power tool and is configured to receive the
accessory. The spindle member defines a longitudinal axis and
includes a second flange provided on an end of the spindle member
and a follower member provided on an opposite end of the spindle
member. The cam member includes a cam surface configured to
interact with the follower surface, the cam member is rotatable
about the longitudinal axis to a clamped position and to an
unclamped position. In the unclamped position the accessory is
removable from the first flange, and in the clamped position the
accessory is clamped between the first flange and the second
flange.
According to another embodiment of the disclosure, a clamping
device for clamping an accessory to a power tool includes a first
clamp member, an actuator, and a second clamp member. The first
clamp member is coupled to a drive system of the power tool and
configured to receive the accessory. The actuator is rotatable
about an axis of rotation to a clamped position and to an unclamped
position. The second clamp member is movable in a direction
parallel to the axis of rotation. The accessory is clamped between
the first clamp member and the second clamp member when the
actuator is rotated to the clamped position. The accessory is
removable from the first clamp member when the actuator is rotated
to the unclamped position.
According to yet another embodiment of the disclosure, a power tool
includes a first flange, a spindle member, a cam member, and an
eccentric member. The first flange is coupled to a drive system and
is configured to receive an accessory tool. The spindle member
defines a longitudinal axis and includes a second flange provided
on an end of the spindle member. The cam member includes a cam
surface configured to interact with an opposite end of the spindle
member, the cam member is rotatable about the longitudinal axis to
an unclamped position and to a clamped position, in the first
position the accessory tool is removable from the first flange, and
in the second position the accessory tool is clamped between the
first flange and the second flange. The eccentric member defines a
spindle opening and a chamfered surface, the spindle member extends
through the spindle opening and the chamfered surface is configured
to bias the accessory tool against the first flange when the cam
member is in the clamped position.
BRIEF DESCRIPTION OF THE FIGURES
The above-described features and advantages, as well as others,
should become more readily apparent to those of ordinary skill in
the art by reference to the following detailed description and the
accompanying figures in which:
FIG. 1 shows a side elevational view of a power tool according to
the present disclosure, the power tool includes a clamping device,
which is shown in the clamped position;
FIG. 2 is a cross sectional view of the power tool of FIG. 1
showing the clamping device in the clamped position without an
accessory bit connected thereto;
FIG. 3 is a cross sectional view of a front portion of the power
tool of FIG. 1 showing the clamping device in the clamped position
without the accessory bit connected thereto;
FIG. 4 is perspective view of the front portion of the power tool
of FIG. 1, showing the clamping device in the clamped position with
an accessory bit/tool connected to the power tool;
FIG. 5 is a cross sectional view of the front portion of the power
tool of FIG. 1, showing an inner flange portion of the clamping
device that is offset from a spindle portion of the clamping
device;
FIG. 6 is a perspective view of a follower member of the clamping
device shown in FIG. 3;
FIG. 7 is a perspective view of a cam member of the clamping device
shown in FIG. 3;
FIG. 8 is a perspective view of a portion of the power tool of FIG.
1, showing the clamping device in an unclamped position;
FIG. 9 is a cross sectional view of the front portion of the power
tool of FIG. 1, showing the clamping device in the unclamped
position;
FIG. 10 is a perspective view of an alternative embodiment of the
follower member for use with the clamping device of the power tool
of FIG. 1;
FIG. 11 is a perspective view of an alternative embodiment of a
spindle for use with the clamping device of the power tool of FIG.
1, the spindle includes an eccentric member positioned near a
flange of the spindle; and
FIG. 12 is a cross sectional view of a portion of an alternative
embodiment of the clamping device of the power tool of FIG. 1
including the spindle and the eccentric member of FIG. 11.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of
the disclosure, reference will now be made to the embodiments
illustrated in the drawings and described in the following written
specification. It is understood that no limitation to the scope of
the disclosure is thereby intended. It is further understood that
the disclosure includes any alterations and modifications to the
illustrated embodiments and includes further applications of the
principles of the disclosure as would normally occur to one skilled
in the art to which this disclosure pertains.
As shown in FIGS. 1 and 2, a power tool 100 is provided for
oscillating/rotating an accessory bit/tool 102. The power tool 100
includes a drive system 104 and a clamping device 108 at least
partially positioned within a housing 112. The clamping device 108
is configurable in clamped position and an unclamped position. In
the clamped position the clamping device 108 connects the accessory
bit 102 to the power tool 100. In the unclamped position the
accessory bit 102 is removable from the power tool 100.
The drive system 104 includes an electric motor 116 and a
transmission 120. The electric motor 116 includes a motor shaft 124
and is provided as any electric motor known to those of ordinary
skill in the art. The transmission 120 is coupled to the motor
shaft 124 and includes a drive lever 128. In the embodiment shown
in FIG. 2, the transmission 120 converts rotation of the motor
shaft 124 into oscillatory movement of the drive lever 128 about an
axis of oscillation 168, as will be recognized by those of ordinary
skill in the art. A lubricant 130 (FIG. 3), such as grease, is
included in the housing 112 and is in contact with the drive lever
128.
With reference to FIG. 3, the clamping device 108 includes a spool
132, a clamp member provided as an outer flange 136, a clamp member
provided as an inner flange 140, a spindle 144, a follower member
148, an actuator provided as a cam 152, a biasing spring 156, and a
handle 160. The spool 132 is rotatably supported in the housing 112
by an upper bearing assembly 164 and a lower bearing assembly 166.
The upper bearing assembly 164 is provided as a needle bearing
assembly, but may be any type of bearing assembly. The lower
bearing assembly 166 is provided as a roller bearing, but may also
be any type of bearing assembly. The spool 132 defines a cavity 172
in which the biasing spring 156 and the spindle 144 are at least
partially positioned. A lower portion 176 of the spool 132 extends
from the housing 112. The spool 132 is coupled to the drive lever
128. Accordingly, the spool 132 oscillates about the axis of
oscillation 168, along with the drive lever 128, when the motor 116
is energized. Specifically, the spool 132 rotates back and forth
through a range of approximately two degrees (2.degree.) to three
degrees (3.degree.) of rotation.
As shown in FIG. 3, the outer flange 136 is fixedly connected to
the lower portion 176 of the spool 132 and is positioned outside of
the housing 112. The outer flange 136 is coupled to the drive
system 104 through the spool 132. The outer flange 136 oscillates
about the axis of oscillation 168 with the spool 132 and in the
same manner as the spool when the electric motor 116 is
energized.
Referring now to FIG. 4, the outer flange 136 receives the
accessory bit 102 and, to this end, includes a plurality of
protrusions 180. The protrusions 180 extend away from a contact
surface 184 of the flange 136 in a circular pattern centered about
the axis of oscillation 168. As shown in FIG. 5, each protrusion
180 has a side surface 188, which is perpendicular to the generally
flat contact surface 184, such that a portion of each of the
protrusions exhibits a uniform shape as viewed along the axis of
oscillation 168. Stated differently, the side surface 188 portion
of each protrusion 180 is not tapered. It is noted that a tip
portion 189 of each of the protrusions 180 may a rounded over or
beveled edge to assist in connecting the accessory bit 102 to the
power tool 100. The perpendicular side surfaces 188 enable the
outer flange 136 to receive the accessory 102 with very little
clearance being exhibited between the accessory and the outer
flange.
With reference to FIG. 5, the inner flange 140 is provided on an
end of the spindle 144 near the outer flange 136. The inner flange
140 defines a generally circular periphery 190. A center point 192
of the circular periphery 190 is offset from the axis of
oscillation 168, such that a greater portion of the inner flange
140 is positioned on one side of the axis of oscillation (i.e.
toward the front of the power tool 100) than is positioned on an
opposite side of the axis of oscillation (i.e. toward the rear of
the power tool 100). The circular periphery 190 has a chamfered
edge 196 that engages the accessory bit 102 and biases the
accessory bit against the outer flange 136. It is noted that the
center point 192 of the inner flange 140 is defined as the center
of the circular flange. Other embodiments of the inner flange 140,
however, may be non-circular and specifically, may be irregularly
shaped. In these embodiments, the center point 192 of the inner
flange 140 may be the centroid of the inner flange.
With reference again to FIG. 3, the spindle 144 extends upward from
the inner flange 140 through the cavity 172 in the spool 132. The
spindle 144 defines a longitudinal axis 200 that is coaxial with
the axis of oscillation 168. The spindle 144 and the inner flange
140 are moveable in a direction parallel to the axis of oscillation
168; however, the spindle is fixedly connected to the power tool
100 and is not removable from the power tool during the normal
course of operation, including when the accessory bit 102 is
removed from the power tool 100.
As shown in FIG. 3, the follower member 148 is fixed to an upper
end of the spindle 144 opposite to the inner flange 140 and extends
further outward from the spindle. The follower member 148 is at
least partially positioned within the cavity 172 of the spool 132.
An isolated perspective view of the follower member 148 is shown in
FIG. 6. The follower member 148 is a unitary component and includes
a first protrusion 204 and a second protrusion 208 integrally
formed therewith. The first protrusion 204 and the second
protrusion 208 each have a corresponding follower surface 212, 216
that engages and/or interacts with the cam 152. The follower 148
has a generally circular periphery and the first protrusion 204 is
located on a diametrically opposite side from the second protrusion
208.
Referring again to FIG. 3, the cam 152 of the clamping device 108
is positioned within the housing 112 above the follower member 148
and at least partially within the cavity 172 in the spool 132. An
isolated perspective view of the cam 152 is shown in FIG. 7. The
cam 152 defines a generally circular periphery 220 having a center
point 224 that is aligned with the axis of oscillation 168. The cam
152 includes a cam surface 228 positioned to interact with the
follower member 148. The cam surface 228 includes a first inclined
surface 232 and a second inclined surface 236. The first inclined
surface 232 is positioned to interact with the follower surface 212
of the first protrusion 204, and the second inclined surface 236 is
positioned to interact with the follower surface 216 of the second
protrusion 208.
The cam 152 further includes a first detent 240, a second detent
244, a first backstop 248, and a second backstop 252. The first
detent 240 is positioned at an end of the first inclined surface
232, and the second detent 244 is positioned at an end of the
second inclined surface 236. The detents 240, 244 are shaped to
receive a corresponding one of the protrusions 204, 208 when the
cam 152 is rotated to the unclamped position and to maintain the
position of the cam in the unclamped position. The protrusions 204,
208 are released from the detents 240, 244 when the cam 152 begins
rotating to the clamped position. The first backstop 248 and the
second backstop 252 extend radially outward from the cam 152. Each
backstop 248, 252 is positioned to abut a corresponding portion
(not shown) of the housing 112 when the cam 152 rotated to the
clamped position; thereby, preventing further rotation of the cam.
Some embodiments of the cam 152 may not include the backstops 248,
252.
The cam 152 is rotatably positioned within the housing 112 for
rotation about the center point 224 between a clamped position
(FIGS. 2 and 3) and an unclamped position (FIG. 9). When the cam
152 is in the clamped position the clamping device 108 is in the
clamped position, and when the cam is in the unclamped position the
clamping device is in the unclamped position.
With reference again to FIG. 3, the handle 160 of the clamping
device 108 is connected to the cam 152 with a fastening member
shown as a screw 256, such that rotation of the handle results in
rotation of the cam. The handle 160 is shown in FIGS. 2 and 3, with
the clamping device 108 in the clamped position, and the handle is
shown in FIGS. 8 and 9, with the clamping device in the unclamped
position. As shown in FIG. 8, the handle 160 includes a lock tab
258 that interacts with a detent 262 formed in the housing 112 to
secure the handle and the clamping device 108 in the clamped
position.
As shown in FIG. 3, the biasing spring 156 is a compression spring
positioned in the cavity 172 of the spool 132 between a bottom seat
266 of the spool and the follower member 148. The spring 156 biases
the follower member 148, the inner flange 140, and the spindle 144
toward the cam 152 for each position of the cam. When the outer
flange 136 has received an accessory bit 102 and the clamping
device 108 is in the clamped position, the biasing spring 156
biases the inner flange 140 against the accessory bit, thereby
clamping the accessory bit between the inner flange and the outer
flange.
The components of the clamping device 108 are formed from hard and
wear resistant materials. Accordingly, the spool 132, the outer
flange 136, the inner flange 140, the spindle 144, the follower
148, and the cam 152 may be formed from metal, hard plastics,
and/or other like materials as known by those of ordinary skill in
the art.
Referring to FIGS. 4 and 8, the accessory bit 102 is provided as an
oscillating tool accessory bit including a cutting portion 260 and
a connection portion 264. The cutting portion 260 has a working end
268 (FIG. 8) for shaping/cutting a workpiece (not shown). As shown
in FIG. 4, the connection portion 264 is received by the outer
flange 136 and defines a spindle opening 272, a spindle slot 276,
and a plurality of protrusion openings 280. The spindle opening 272
is a generally circular opening having a diameter that is greater
than the maximum diameter of the spindle 144 and that is smaller
than the diameter of the inner flange 140. A center point 284 of
the spindle opening 272 is aligned with the center point 192 of the
inner flange 140 when the accessory 102 is clamped to the power
tool 100. The spindle slot 276 has a width that is greater than the
diameter of the spindle 144 to enable the accessory 102 to be
received and removed from the spindle. The protrusion openings 280
are positioned around the center point 284 in alignment with the
protrusions 180 on the outer flange 136. The protrusion openings
280 are sized to receive the protrusions 180 with very little
clearance between the protrusions 180 and the protrusion openings
280.
In operation, the clamping device 108 securely clamps the accessory
bit 102 to the power tool 100, and is quickly and easily
manipulated to release the accessory bit from the power tool. As
shown in FIG. 3, the clamping device 108 is in the clamped position
without an accessory bit 102 clamped between the outer flange 136
and the inner flange 140. To connect an accessory bit 102 to the
power tool 100 the clamping device 108 is first moved to the
unclamped position by rotating the handle 160 approximately
140.degree. to 190.degree., and in one particular embodiment about
150.degree.. No separate tools are needed to move the clamping
device 108 to the unclamped position.
Movement of the clamping device 108 from the clamped position to
the unclamped position, results in the inner flange 140 being moved
in a downward direction 288 (FIG. 9) away from the outer flange
136. In particular, rotation of the handle 160 results in rotation
of the cam member 152 relative to the follower 148. Accordingly, as
the cam member 152 is rotated toward the unlocked position, the
portions of the inclined surfaces 232, 236 in contact with the
follower surfaces 212, 216 are positioned increasingly further in
the downward direction 288, thereby forcing the follower 148, the
spindle 144, and the inner flange 140 to move in the downward
direction against the force of the biasing spring 156 to the
position shown in FIG. 9. In this way, the profile of the cam
surface 228 determines the distance that the inner flange 140 moves
as the handle is moved from the clamped position to the unclamped
position.
When the handle 160 reaches the unclamped position, the protrusions
204, 208 become seated in the detents 240, 244 in the cam member
152 under the force of the biasing spring 156. The handle 160 is
moved easily to the unclamped position since the inclined surfaces
232, 236 of the cam surface 228 offer a mechanical advantage when
compressing the biasing spring 156, and also since the length of
the handle offers a mechanical advantage when rotating the cam 152.
Therefore, the clamping device 108 is operable by users of
virtually all skill levels including users with reduced manual
dexterity.
As shown in FIG. 9, when the clamping device 108 is in the
unclamped position the inner flange 140 is separated from the outer
flange 136 and the accessory bit 102 may be received by the outer
flange. To connect the accessory bit 102 to the outer flange 136
the spindle 144 is moved through the spindle slot 276 (FIG. 4) and
into the spindle opening 272 (FIG. 4). Next, the protrusion
openings 280 are aligned with the protrusions 180 and the
connection portion 264 is moved in an upward direction 292 (FIG. 9)
until the protrusions extend through the protrusion openings. The
spindle 144 is not removed from the power tool 100 during
connection of the accessory bit 102 to the power tool.
With the accessory bit 102 received by the outer flange 136, the
handle 160 is moved to the clamped position to clamp the connection
portion 264 of the accessory bit 102 between the inner flange 140
and the outer flange. The cam 152 is rotated relative to the
follower 148 as the handle 160 is moved to the clamped position. As
the cam 152 is rotated, the protrusions 204, 208 exit the detents
240, 244 and the portions of the inclined surfaces 232, 236 in
contact with the protrusions are moved increasingly further in the
upward direction 292. During this time, the biasing spring 156
maintains the follower surfaces 212, 216 of the protrusions 204,
208 against the inclined surfaces 232, 236, such that the follower
member 148, the spindle 144, and the inner flange 140 move in the
upward direction 292 relative to the outer flange 136 under the
force of the biasing spring. This movement brings the inner flange
140 into contact with the accessory 102. When the handle 160 is
rotated to the clamped position the biasing spring 156 forces the
inner flange 140 firmly in the direction of the outer flange 136 to
clamp the connection portion 264 between the inner flange and the
outer flange. Also in the clamped position, an air gap 290 may be
formed between the cam 152 and the follower 148, such that the cam
surface 228 does not contact the follower surfaces 212, 216 when
the clamping device 108 is in the clamped position.
After the accessory bit 102 is clamped to the power tool 100, the
electric motor 116 may be energized to cause the accessory bit to
oscillate. With reference to FIG. 2, the oscillation of the drive
lever 128 causes the spool 132 to oscillate. The oscillation of the
spool 132 is transferred to the outer flange 136 and to the
connection portion 264 of the accessory bit 102. The working end
268 of the oscillating accessory bit 102 may be placed in contact
with a workpiece to cut or shape the workpiece. In general, the
accessory bit 102 oscillates through a range of approximately two
to three degrees.
With reference to FIGS. 5 and 6, the offset position of the inner
flange 140 in relation to the axis of oscillation 168 along with
the chamfered edge 196 enables the clamping device 108 to clamp the
accessory bit 102 to the power tool 100 with a substantially
zero-clearance connection (i.e. with substantially zero "play"
between the accessory bit and the outer flange 136). When the
clamping device 108 is moved to the clamped position the chamfered
edge 196 contacts the spindle opening 272. Upon initial contact the
center point 192 of the inner flange 140 and the center point 284
of the spindle opening 272 are offset. However, since the chamfered
edge 196 is biased against the spindle opening 272 by the biasing
member 156, a force is exerted on the connection portion 264 in a
direction that tends to move the center point 284 of the connection
portion into alignment with the center point 192 of the inner
flange 140. Accordingly, this force causes the inner flange 140 to
bias the protrusion openings 280 firmly against the side surfaces
188 of the protrusions 180 and to establish the substantially
zero-clearance connection.
The substantially zero-clearance connection between the outer
flange and the accessory bit 102 increases the efficiency of the
torque transferred from the drive system 104 to the accessory bit.
The increase in efficiency is exhibit by increased oscillation in
the working end 268 of the accessory bit 102 and less heat
generated between the connection portion 264 and the clamping
device 108, as compared to other similar power tools.
The side surfaces 188 of the protrusions 180 also increase the
efficiency of the torque transferred from the drive system 104 to
the accessory bit 102 under some load conditions of the accessory
bit. As shown in FIG. 5 the connection portion 264 is seated firmly
against the contact surface 184 of the outer flange 136. Under some
load conditions, however, the connection portion 264 may be moved
away from the contact surface 184. Nonetheless, the substantially
zero-clearance connection is maintained between the connection
portion 264 and the outer flange 136 due to the perpendicularly
extending side surfaces 188, which maintain full contact with the
protrusion openings 280 even when the connection portion 264 is not
completely seated on the contact surface 184.
FIG. 10 shows another embodiment of the follower 148'. The follower
148' functions in the same manner as the follower 148, except that
the protrusions 204', 208' of the follower 148' are fixedly
connected to the follower member 148' instead of being integrally
formed therewith. The protrusions 204', 208' are generally
cylindrical and include a rounded-over contact surface 212', 216'
that interacts with the cam surface 228.
FIGS. 11 and 12, show another embodiment of the inner flange 140',
which includes a flange surface 292' and an eccentric member 296'.
The inner flange 140' defines a generally circular periphery 190'
having a center point 192' (FIG. 11) that is coaxial with the axis
of oscillation 168 and the longitudinal axis 200'. The flange
surface 292' contacts the accessory bit 102 when the clamp device
108 is in the clamped position.
The eccentric 296' is positioned on the flange surface 292' and has
a center point 300' that is offset from the axis of oscillation
168'. The center point 300' of the eccentric 296' may be determined
in numerous ways as known by those of ordinary skill in the art,
including by determining the centroid of the eccentric. The
eccentric 296' has a chamfered edge 304' that engages the spindle
opening 272 of the accessory bit 120 in a manner similar to the
manner in which the chamfered edge 196 engages the spindle opening
272 to cause the protrusion openings 280 to be biased against the
protrusions 180. The eccentric 296' may be formed from materials
including metal, hard plastics, and the like.
While the power tool 100 has been illustrated and described in
detail in the drawings and foregoing description, the same should
be considered as illustrative and not restrictive in character. For
example, the power tool 100 has been described as an oscillating
power tool; however, the power tool may also be provided as a
rotary tool configured to rotate the accessory bit 102. It is
understood that only the preferred embodiments have been presented
and that all changes, modifications and further applications that
come within the spirit of the disclosure are desired to be
protected.
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